DE1188571B - Process for the chlorination of hydrocarbons or chlorinated hydrocarbons - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C07c

German class: 12 ο - 2/01

Number: 1188 571

File number: C 24544IV b / 12 ο

Filing date: July 6, 1961

Opening day: March 11, 1965

In the production of chlorinated hydrocarbons by high-temperature chlorination of gaseous saturated or unsaturated hydrocarbons, such as. B. methane, ethane, ethylene, propane, propylene, etc. _s arise in addition to the desired chlorinated hydrocarbons as a by-product of chlorinated hydrocarbons, which are difficult to exploit economically because their possible uses are limited. These are predominantly hexachloroethane, hexachlorobutadiene and hexachlorobenzene (Ullmann, Enzyklopadie der technischen Chemie, 1954, Vol. 5, p. 412; Asinger, Chemie und Technologie der Paraffin-Hydrocarbons, 1956, p. 209). Since, depending on the chlorination process and the chlorination conditions, these products are obtained in amounts of about 5 to 20%, possibly even more, their formation leads to high chlorine losses.

As a rule, it is even necessary to destroy these products with considerable effort, since they cannot be discharged into the wastewater.

It is known to add aliphatic or low-chlorinated hydrocarbons with hexachloroethane of chlorine to chlorinate (German Auslegeschrift 1 058 037). The hexachloroethane splits in the process thermally in perchlorethylene and free chlorine, which then chlorinates the hydrocarbons present:

6C ₂ Cl ₆ - + - 6C ₂ Cl ₄ + 6Cl ₂ 6 Cl ₂ + 2 CH ₄ - »- C ₂ Cl ₄ + 8 HCl

This reaction enables the hexachloroethane to be used profitably by recycling it back into the chlorination zone.

However, it does not succeed in using this process to produce hexachlorobutadiene and hexachlorobenzene in a similar way Way to react. Both substances are so thermally stable that they form the reaction zone run through almost unchanged.

For this reason, it has so far been expressly waived these chlorinated hydrocarbons in the Circuit returned to the chlorination process. So are in the chlorination of dichloroethylene to the tri- and perchlorethylene the by-products tetrachlorethylene, pentachloroethane and Hexachloroethane and unreacted dichloroethylene are recycled, while the hexachlorobutadiene and hexachlorobenzene, which are said to be non-recyclable, are separated off by distillation must (Chimie et Industrie 83, p. 563, column 1, line 3 ff. [1960]). Also in the German exposition 1,095,268, column 1, line 14, is used to recycle the secondary processes formed in the chlorination of propane for the chlorination of hydrocarbons or chlorinated hydrocarbons

Applicant:

Chemical works Hüls Aktiengesellschaft,

Marl (district of Recklinghausen)

Named as inventor:

Dr. Alfred Schmidt,

Dr. Joachim Tiesler, Marl (district of Recklinghausen)

products stated that hexachlorobenzene and hexachlorobutadiene cannot be recycled and cause an increased consumption of raw material.

Surprisingly, it has now been found that recycling of the hexachlorobutadiene despite its inertia is unexpectedly beneficial.

It has been found that the formation of the undesired hexachlorobutadiene in the chlorination lower aliphatic, straight-chain, saturated or corresponding monounsaturated hydrocarbons or one to three times chlorinated methanes or one to two times chlorinated ethanes at 500 to 900 ° C Can largely change by adding hexachlorobutadiene alone or as a mixture to the reaction zone with recycled hydrocarbons or chlorinated hydrocarbons.

If you constantly return the entire amount of hexachlorobutadiene that has also formed, you will find in the reaction product considerably less of this chlorinated hydrocarbon than, as expected, the The sum of the amount normally produced and returned. One can access this Wise so largely suppress the emergence of this unwanted by-product. The procedure thus allows a better utilization of the hydrocarbons used and the chlorine and reduces the expenditure for the removal of the undesired, unusable by-products.

Particularly advantageous temperatures for the process are between 500 and 700 ° C.

According to the process, a certain amount of the hexachlorobutadiene can continuously be in the reaction zone are supplied from a supply; a particularly advantageous embodiment of the method consists in that the chlorination product is uninterrupted

509 518/463

Claims (1)

3 4 Separates by distillation and the resulting hexachlorobutadiene under otherwise identical conditions, but with one constantly returns in the cycle. The introduction temperature of 855 ° C ₃ are in 1980 g of reaction only 2.4% = 49.6 hexachlorobutadiene can be produced by gasification or injection into one of the mixtures Both gas streams - chlorine or hydrocarbon - found that is even 9.4 g less than used. substance - or in a mixture thereof. 5 _. The new formation of the undesired hexachloro B e ι s ρ ι e 1 2 Butadiene is also reduced if, in addition to the In an electrically heated quartz tube of 4.50 m Hexachlorobutadiene still other byproducts, the length and a clear width of 19 mm were at in the reaction zone in a known manner by 550 ° C 375 g / h evaporated 1,2-dichloroethane and set, are recycled, for example Tetralio 600 g of chlorine (molar ratio 1: 2.2) implemented. Of the chloroethane, pentachloroethane or hexachloroethane. The experiment was completed after 2.4 hours (total use In some cases it is advantageous to stop the hexachloro (900 g dichloroethane and 1420 g chlorine), butadiene not mixed with the gas streams, a total of 1281 g of reaction products but in liquid or atomized form at or with a content of 12.9 percent by weight = 165 g feed several points directly to the reaction zone. 15 obtained hexachlorobutadiene. The experiment was carried out under the same conditions Example 1 repeated and in addition to the 900 g of dichloro In an electrically heated glass tube of 30 mm ethane, 100 g of hexachlorobutadiene evaporated. There were 500 mm diameter and length at 830 to 1,310 g of a chlorinated hydrocarbon mixture with 85O ⁰ C per hour 8001 2251 chlorine and methane environmentally = ergesetzt 208 g hexachlorobutadiene 20 15.9 weight percent. After a test duration of 1.5 hours, the expected 165 + 100 = 265 g. a total of 1920 g of a chlorinated hydrocarbon mixture "
obtained with 59.8% carbon tetrachloride, 0.2% claim:
Chloroform, 36.2% perchlorethylene, 0.7% hexachloro process for the chlorination of lower aliphatic, ethane, 1.3% = 25 g hexachlorobutadiene, 1.6% hexa- 25 straight-chain, saturated or corresponding einchlorbenzoi. The experiment is repeated under the same polyunsaturated hydrocarbons or conditions, 59 g of hexachlorobuta- to triple-chlorinated methanes or mono- to diene being evaporated into the methane stream. This corresponds doubly chlorinated ethanes at 500 to 900 ⁰ C, avowed chlorine hydrocarbon mixture (2050 g) corresponds characterized in that g in holding only 3.2% = 65.7 hexachlorobutadiene, or 30 the reaction zone hexachlorobutadiene alone or only 6 , 7 g above the added amount of 59 g, mixed with recycled hydrocarbons, while 25 g were formed without addition. or introduces chlorinated hydrocarbons. 509 518/463 3.65 © Bundesdruckerei Berlin